IMPORTANCE: Understanding the pathogenic mechanisms of Fuchs endothelial corneal dystrophy (FECD) could contribute to developing gene-targeted therapies. OBJECTIVE: To investigate associations between demographic data and age at first keratoplasty in a genetically refined FECD cohort. DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study recruited 894 individuals with FECD at Moorfields Eye Hospital (London) and General University Hospital (Prague) from September 2009 to July 2023. Ancestry was inferred from genome-wide single nucleotide polymorphism array data. CTG18.1 status was determined by short tandem repeat and/or triplet-primed polymerase chain reaction. One or more expanded alleles (≥50 repeats) were classified as expansion-positive (Exp+). Expansion-negative (Exp-) cases were exome sequenced. MAIN OUTCOMES AND MEASURES: Association between variants in FECD-associated genes, demographic data, and age at first keratoplasty. RESULTS: Within the total cohort (n = 894), 77.3% of patients were Exp+. Most European (668 of 829 [80.6%]) and South Asian (14 of 22 [63.6%]) patients were Exp+. The percentage of female patients was higher (151 [74.4%]) in the Exp- cohort compared to the Exp+ cohort (395 [57.2%]; difference, 17.2%; 95% CI, 10.1%-24.3%; P < .001). The median (IQR) age at first keratoplasty of the Exp + patients (68.2 years [63.2-73.6]) was older than the Exp- patients (61.3 years [52.6-70.4]; difference, 6.5 years; 95% CI, 3.4-9.7; P < .001). The CTG18.1 repeat length of the largest expanded allele within the Exp+ group was inversely correlated with the age at first keratoplasty (β, -0.087; 95% CI, -0.162 to -0.012; P = .02). The ratio of biallelic to monoallelic expanded alleles was higher in the FECD cohort (1:14) compared to an unaffected control group (1:94; P < .001), indicating that 2 Exp+ alleles were associated with increased disease penetrance compared with 1 expansion. Potentially pathogenic variants (minor allele frequency, <0.01; combined annotation dependent depletion, >15) were only identified in FECD-associated genes in 13 Exp- individuals (10.1%). CONCLUSIONS AND RELEVANCE: In this multicenter cohort study among individuals with FECD, CTG18.1 expansions were present in most European and South Asian patients, while CTG18.1 repeat length and zygosity status were associated with modifications in disease severity and penetrance. Known disease-associated genes accounted for only a minority of Exp- cases, with unknown risk factors associated with disease in the rest of this subgroup. These data may have implications for future FECD gene-targeted therapy development.

• MeSH
• celogenomová asociační studie MeSH
• dospělí MeSH
• Fuchsova endoteliální dystrofie * genetika   chirurgie   epidemiologie   diagnóza   MeSH
• genetická predispozice k nemoci * MeSH
• jednonukleotidový polymorfismus * MeSH
• lidé středního věku MeSH
• lidé MeSH
• retrospektivní studie MeSH
• rizikové faktory MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• stupeň závažnosti nemoci MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• pozorovací studie MeSH

Corneal dystrophies are a group of predominantly rare inherited disorders. They are by definition bilateral, relatively symmetrical, and without systemic involvement, affecting corneal transparency and/or refraction. Traditional classification of corneal dystrophies is based on slit-lamp appearance, affected corneal layer and histological features. Molecular genetics has provided ultimate proof for the existence of distinct corneal dystrophies and discarded duplicates in their terminology. Currently, there are at least 16 genes with identified pathogenic variants implicated in corneal dystrophies. Herein, we summarise contemporary knowledge on genotype-phenotype correlations of corneal dystrophies, including a critical review of some reported variants, along with the understanding of the underlying pathogenic dystrophic process; essential knowledge for the development of targeted therapies.

• Klíčová slova
• corneal dystrophy, genetics, hereditary, molecular biology,
• MeSH
• dědičné dystrofie rohovky * genetika   terapie   MeSH
• fenotyp MeSH
• genetické asociační studie * MeSH
• genotyp MeSH
• lidé MeSH
• molekulární biologie MeSH
• mutace * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

BACKGROUND: Fuchs endothelial corneal dystrophy (FECD) is the most common repeat-mediated disease in humans. It exclusively affects corneal endothelial cells (CECs), with ≤81% of cases associated with an intronic TCF4 triplet repeat (CTG18.1). Here, we utilise optical genome mapping (OGM) to investigate CTG18.1 tissue-specific instability to gain mechanistic insights. METHODS: We applied OGM to a diverse range of genomic DNAs (gDNAs) from patients with FECD and controls (n = 43); CECs, leukocytes and fibroblasts. A bioinformatics pipeline was developed to robustly interrogate CTG18.1-spanning DNA molecules. All results were compared with conventional polymerase chain reaction-based fragment analysis. FINDINGS: Analysis of bio-samples revealed that expanded CTG18.1 alleles behave dynamically, regardless of cell-type origin. However, clusters of CTG18.1 molecules, encompassing ∼1800-11,900 repeats, were exclusively detected in diseased CECs from expansion-positive cases. Additionally, both progenitor allele size and age were found to influence the level of leukocyte-specific CTG18.1 instability. INTERPRETATION: OGM is a powerful tool for analysing somatic instability of repeat loci and reveals here the extreme levels of CTG18.1 instability occurring within diseased CECs underpinning FECD pathophysiology, opening up new therapeutic avenues for FECD. Furthermore, these findings highlight the broader translational utility of FECD as a model for developing therapeutic strategies for rarer diseases similarly attributed to somatically unstable repeats. FUNDING: UK Research and Innovation, Moorfields Eye Charity, Fight for Sight, Medical Research Council, NIHR BRC at Moorfields Eye Hospital and UCL Institute of Ophthalmology, Grantová Agentura České Republiky, Univerzita Karlova v Praze, the National Brain Appeal's Innovation Fund and Rosetrees Trust.

• Klíčová slova
• Fuchs endothelial corneal dystrophy, Optical genome mapping, Somatic mosaicism, Tissue-specific repeat instability, Trinucleotide repeat expansion disease, Triplet repeat expansion-mediated disease,
• MeSH
• alely MeSH
• expanze trinukleotidových repetic MeSH
• Fuchsova endoteliální dystrofie * genetika   patologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mapování chromozomů MeSH
• nestabilita genomu MeSH
• orgánová specificita genetika   MeSH
• senioři MeSH
• transkripční faktor 4 * genetika   metabolismus   MeSH
• trinukleotidové repetice genetika   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• TCF4 protein, human MeSH Prohlížeč
• transkripční faktor 4 * MeSH